Disc valve for vacuum board



March 7, 1967 J. M. cocrro DISC VALVE FOR VACUUM BOARD Filed April l2,1965 INVENTOR ATTORNEYJ' iUnited States Patent Office 3,307,819 PatentedMar. 7, 1967 3,307,819 DISC VALVE FR VACUUM BOARD Joe Michael Cocito,11008 Nicholas Drive, Wheaton, Md. 20902 Filed Apr. 12, 1965, Ser. No.447,190 12 Ciaims. (Cl. 248-363) This invention relates to vacuumholders for thin fiexible photographic sheets or films of the typehaving a large number of suction holes distributed over the surface of asupporting plate, and more particularly relates to improved valve meansfor automatically reducing the flow of air into vacuum holes which arenot covered by a photographic sheet bein-g supported by the holder.

It is a principal object of this invention to provide a holder of theabove -type in which novel and improved automatic valve means areprovided at each suction hole to virtually close the bore extending fromthe front face of the plate into a vacuum manifold located behind theplate whenever no film or sheet overlies and closes the bore, and saidvalve means automatically opening when a -flm is laid thereover.

I am aware that there are a number of prior-art patents showingstructures which operate in this same general way, for instance Patents2,910,265, 2,753,181, 2,782,574, 2,694,337, 2,425,921 and 2,198,765, butthe present valve structure is an improvement from the point of view ofsimplicity and from the point of view of being self-cleaning to agreater extent. One of the most serious problems encountered inconnection with valved vacuum-board structures results from theirtendency to collect dust in the bores of the suction holes with theresult that the valves 'become jammed or the bores clogged, or both.

The present invention teaches simplified valve means which lby virtue ofimproved structure have less tendency to become jammed. The presentvalve means takes the form of a disc member located within a major boreportion, and having a spring feature which maintains the valve means inopen position, either the whole disc or a portion thereof beingdisplaceable -by vacuum in the manifold toward a closed position atwhich the valve means imperfectly closes the bore, thereby leaving asmall leakage space. This structure provides the desired valving action,without however, completely closing the bore to the ow of air so thatwhen the outer end of the bore is closed by a film laid thereover, theair between the valve means and the film will leak into the manifold bypassing through the i-mperfect seating zone where the valve meansattempts to seat against a shoulder within the bore portion, and thusrelease the air pressure holding the valve means against the shoulder topermit the valve to open. When the valve is in open position, the boreat the shoulder represents a large opening which freely passes anycollected dust or lint into the manifold.

The present disclosure shows the improved valve means coupled with anadvantageous manifold structure located behind the pattern of suctionholes and communicating with the bores therethrough. This structurecomprises a continuous manifold including a lengthy channel which isfolded in a serpentine manner and communicates with all of the suctionpoints sequentially. A vacuum is drawn upon the channel at one end, andthe channel is of such small cross-sectio-nal area that when the systemis first turned on, the evacuating effort will be applied initially to arelatively few valve means near the beginning of the serpentine channel.When these valve means have closed, the vacuum gradient will move alongthe channel causing each valve means which it approaches to close in asequential manner. Therefore, the vacuum pump need not be capable ofclosing substantially all of the ball valves simultaneously, lbut ratherthe pump need be capable only of closing a few of the valve means at anyone time.

Another object of this invention is to provide a relatively simple andeasily machined structure which can be economically manufactured usinginexpensive materials. One improvement in the present structure is theprovision of press-fit washer means for holding the valve balls in thebores, the washers being pressed into recesses at the film supportingend of each of the bores. These washers may 'be knurled or otherwiseroughened on their outer surfaces so that when a film is laid over thewasher, the vacuum from the central hole therethrough can spreadoutwardly through the grooves provided in the front face of the washersby the surface knurling, but these grooves are so small and shallow ascompared with the diameter of the hole through the washer that in theevent that the film overlies only a portion of the washer including thehole therethrough, the holding effect of the vacuum upon the film willnot be lost by escape through those knurled areas of the washers whichare not covered by the film.

Another advantage of the present invention is that virtually all of thenecessary machining can be performed upon both sides of one main panelmember, the other panel member requiring no machining except a few holesdrilled therein to facilitate screwing of the rear closure panel to thefront panel to complete the enclosure of manifold channels.

Other objects and advantages of the present invention will becomeapparent during the following discussion of the drawings, wherein:

FIG. 1 is a broken elevation view of a vacuum film holder according tothe present invention connected with an external vacuum pump, a portionof the front panel of the holder being cut away to show the manifoldconstruction;

FIG. 2 is an enlarged sectional view taken along the line 2-2 of FIG. 1,this figure showin-g the upper valve in open position and the lowervalve in closed position;

FIG. 3 is a sectional view similar to FIG. 2, but showing a firstvalve-structure modification with the upper valve in open position andthe lower valve in closed position;

FIG. 4 is a sectional view similar to FIG. 2 but showing a secondvalve-structure modification with the upper valve in open position andthe low-cr valve in closed position;

FIG. 5 is a plan view of a valve Idisc as used in FIG. 2;

FIG. 6 is a perspective view of a valve member as used in FIG. 3; and

FIG. 7 is a perspective view of a valve menrber as used in FIG. 4.

Referring now to the drawings, the figures show preferred embodiments ofthe invention which include two panel members. The front panel member 1has a large number of holes, arranged in Ia closely proximate patternand passing7 all the way through it. Each of the holes comprises la mainbore portion 2 meeting an enlarged outer portion 3 and a small innerportion 4, these bore portions extending from the front surface 1a ofthe panel 1 through the rear surf-ace 1b thereof. The rear surf-ace hasa series of serpentine channels 5 therein which are separated by ribs 1cand which form a continuous passagev commencing in the center of FIG. 1and winding around the figure and eventually opening into an evacuationoutlet 5a which connects to a suitable vacuum pump P through a suitableconduit C. The rear surfaces of the ribs 1c mate with a rear closurepanel member 10, and the front and rear panels are held together by anysuitable means such as screws 11 as shown in FIGS. 2, 3, and 4.

The manner in which the present valved board is intended to operate isbasically similar to the functioning of numerous other vacuum holderssuch as the ones illustrated in the patents mentioned above in whichvalve means are provided to automatically close any of the bores whichhave not been covered by film sheets F or other relatively non-porousWebs overlying the front face .1a of the panel 1. In the presentdisclo-sure the valve means shown in FIGS 2 and 5 by which the closingof the uncovered bores is accomplished includes a fiat disc 6 located ateach of the major bores 2 and held at its periphery in the larger boreportion 3 by a retainer washer 7 having a hole 7a therethrough andhaving a knurled front face 7b. The disc 6 has a spiral slot 6.atherethrough, and is made of a very thin spring-like .sheet material,such as 'beryllium copper, so that its central area 6b can be distortedtoward and against the end of the bore 4 at the shoulder 2a when avacuum is drawn upon the manifold 5 and when the hole '7a is uncovered.The disc 6 also has a dimple 6c in its innermost convolution so as toprevent the surface 6b from seating perfectly against the shoulder 2.a.This imperfect seating is best seen at the lower half of FIG. 2, andserves the purpose of permitting the air to be exhausted from the bore 2in the event that a sheet F should be placed over the hole 7a, therebypermitting the valve means to automatically open when the hole17a iscovered up.

FIG. 3 shows a first modified form of the invention, in which likereference characters refer to similar structure. However, the ydiscmember 8 which comprises the valve means is not fiat in relaxedcondition as is the disc member 6. Rather it is provided with apermanent set so that its convolutions formed by the spiral slot 8aassume somewhat conical relative locations as shown in FIG. 6. Inrelaxed condition, the member 8 ts in and snugly grips the bore 2 asshown at the top of FIG. 3, and the centr-al portion 8b contacts thewasher 7 in open position. When the valve member S moves to closedposition as shown below in FIG. 3, it lies almost flat against theshoulder 2a, ibut is prevented from perfect seating by the dimple 8c.

FIG. 4 shows a second modified form of the invention in which structurewhich is similar to that shown in FIG. 2 is provided with the samereference numeral. This second modification is also essentially a discwith reciprocates axially of the bore portion 2 to assume an openposition as shown at the top of FIG. 4 wherein the coil spring 12 pushesthis disc 13 yieldably toward the washer 7, but whereby the vacuum canpull the disc 13 to the left to assume Ian imperfectly closed positionas shown below in FIG. 4 wherein the valve leaks between convolutions ofthe spring 12. The disc 13 is slightly smaller in diameter than the boreportion 2, and the spring 12 comprises a cone-shaped helix made of smalldiameter spring wire, for example, 6 thousandths of an inch in diameter.Preferably, the spring 12 should be wound such that the outerconvolutions are closer together than the inner convolutions, wherebywhen the valve is closed as shown below in FIG. 4, any dust which canpass between the outer convolutions to enter the space between the disc13 and the shoulder 2a, can easily ush through the increasingly Widespace between inner convolutions and thereby reach 'and pass through thebore 4. The disc 13 is supported and centered by the spring 12 which isWelded or otherwise attached to its center, -as at 12a.

OPERATION The reasons Vfor the novel structures of the pr-esentdisclosure will be further claried during the following ex planation ofoperation. As is recognized in the prior art, if unlimited vacuum pumpfacilities are available, it is not necessary to close the exposed boreholes through the front panel member in locations not overlapped by thefilm F, but since it is desirable to use only a relatively small vacuumpump P in a practical installation, the closure valves shown in thebores become necessary in order to conserve the vacuum, especially whenonly a small proportion of the bores through the front panel member arecovered by a film F.

In practical working embodiments of the present invention, the chanels 5are milled into or built up upon one of the panel members 1 or 11i, butonly to a depth of about l@ inch, and the width of each channel is aboutfive inches. Since the channels are of relatively small cross-sectionalarea, they exhibit considerable impedance to the flow of airtherethrough with the result that when the vacu-um pump P is lrststarted, the end of the channel nearest the conduit C drops in pressureconsiderably ahead of the time that the pressure begins dropping in themore remotely located channel portions. Thus, even a small pump P, suchas a domestic vacuum cleaner, can sequentially close the valves locatedalong the channel without having to first evacuate the entire manifoldto do so. Hence, when the pump P is started, the valves close first inthe outer channels, and then successively close in a sequence windingaround the panels and approaching the center of the panel members.

Referring now to FIGS. 2, 3, and 4, these figures illustrate novel valvestructures having very practical features. Experience has shown that thepresence of `dust in most valve structures is highly damaging t-o theiroperation, and eventually renders the device inoperative. A majoradvantage of the present structure is that the valving action t-akesplace between several parts which move relative to each other, while thevalve moves between open and closed positions in such a way as todislodge any dust commencing to accumulate. In other words, there is asort of working action between spring convolutions and between the discmembers and the walls of the bore `and shoulder which action encouragesthe air jetting passed these parts to fiush out the clearance space. Asuitable set of dimensions would be a diameter of 3%; inch for the bore2, the disc 13 :being a few thousandths of an inch smaller in diameter.The bore 4 can be drilled by a number 30 twist drill and is thereforeabout .128 inch in diameter, and the washer 7 is 7/16 inch in diameterwith a central hole 7a of the same diameter as the bore 4. The axiallength of the bore 2 should be no less than the maximum radial spacebetween convolutions of the .spring 12 in the showing of FIG. 4, andshould be great enough in the forms shown in FIGS. 2 and 3 to permit asubstantial gap G to Idevelop between convolutions of the disc springs 6and 8 to pass dust through the manifold 5.

The slotted structure of the discs 6 and 8 shown in FIGS. 2, 3, 5, and 6can be easily accomplished by chemically etching the slots 6a `and Sainto beryllium copper discs.

The outer surface 7b of each of the washers 7 is knurled so that minutegrooves will be provided on the outer surface of each washer 7permitting a vacuum to be drawn on the film F over as much of thesurface area of the washer 7 as is covered thereby, and not merely overthe relatively small area of the hole 7a. Some prior art patents haveshown other types of roughening of the outer surface in the vicinity ofeach suction hole, but many of these structures require expensiveconcentric-groove machining of the front plate itself. The presentinvention is believed to constitute a practical improvement by requiringonly inexpensive knurling of the washers themselves before they areinstalled in the bores 3 of the front panel.

The present invention is not to be limited to the exact structure shownin the drawings, for obviously changes may be made therein within thescope of the following claims.

I claim:

1. A vacuum board for holding liex'ible sheets in a plane, comprising:

(a) a panel member having plural suction holes therethrough, eachincluding a bore extending from the front face of said membertherethrough to the rear and having a shoulder therein at a locationwhere the bore changes from a larger front bore portion to a smallerbore portion extending through the rear of the panel member;

(b) vacuum manifold means on the rear of the panel and communicatingwith said bores;

(c) disc and spiral spring means in said larger bore portion, the discmeans fitting snugly therewithin and having a central area locatedopposite said smaller bore portion and urged away therefrom by saidspring means, and said disc and spring means being movable by air-flowin the larger bore portion toward said manifold means to displace saidcentral area toward sai-d shoulder and restrict the -smaller boreportion; and

(d) means for preventing perfect seating of the disc means on theshoulder in the vicinity of the smaller bore portion.

2. In a board as set forth in claim 1, said disc and spring meanscomprising a thin flat disc of spring-like sheet material with a spiralslot extending from a location near to but offset from its centerthrough plural convolutions to a point near the perihpery of the disc,and the disc being supported at its periphery in the larger bore portionparallel to and spaced from the shoulder, and the central area of thedisc being displaceable by the vacuum in the manifold means into contactwith the shoulder to overlie the smaller bore; and said preventing meanscomprising a distortion of the central area thereof to provide imperfectseating against the shoulder.

3. In a b-oard as set forth in claim 1, said disc and spring meanscomprising a thin disc of spring like sheet material with a spiral slotextending from a location near to but offset from its center outwardlythrough plural convolutions, and the disc being supported in the largerbore portion with its periphery against the shoulder, the central areaof the disc being normally out of contact with the shoulder at thesmaller bore and being displace able by the vacuum in the manifold meansinto contact therewith; and said preventing means comprising adistortion of the central area of the disc to provide imperfect seatingagainst the shoulder.

4. In a board as set forth in claim 1, said disc and spring meanscomprising a fiat disc sized to slide freely in said larger boreporti-on, a spiral spring having its center attached to the central areaof the disc and spiralling through plural convolutions away therefromand terminating in an outer convolution sized to grip the wall of thelarger bore portion and disposed at said shoulder, and the springnormally holding the disc remote from the shoulder but yielding topermit at nesting of its convolutions between the shoulder and the discwhen the latter is attracted toward the former by the vacuum manifoldmeans, said preventing means comprising the nested convolutions of thespring leaving a leakage space therebetween.

S. In a board as set forth in claim 4, the spiral spring being woundsuch that the space between its convolutions when nested increases fromminimum spacing near the outer convolutions to maximum spacing near theinner convolutions.

6. A vacuum board for holding flexible sheets in a plane, comprising:

(a) a panel member having plural suction holes therethrough, eachincluding a bore extending from the front face of sai-d membertherethrough to the rear and having a shoulder therein at a locationwhere the bore changes from a larger front bore portion to a smallerbore portion extending through the rear of the panel member;

(b) vacuurnrn'anifold. means on the rear `of the panel and communicatingwith said bores;

(c) vacuum-operated valve means in each suction hole and comprising discand spring means contained within a larger portion 'of the bore, thespring means having plural convolutions with an outer convolutioncontacting the bore to maintain the spring means in place therein and aninner convolution yieldably urging a central portion of the disc meansaway from the shoulder, said central portion being large enough to coverthe end of the smaller bore portion at the shoulder; and

(d) means for preventing perfect seating of the central portion of thedisc means on the shoulder in the vicinity of the smaller bore portion.

7. In a board -as set forth in claim 6, said disc and spring meanscomprising a thin at disc of spring-like sheet material with a spiralslot extending from a location near to but offset from its centerthrough plural convolutions to a point near the periphery of the disc,and the disc being supported at its periphery in the larger bore portionparallel to and spaced from the shoulder, and the central portion of thedisc being displaceable by the vacuum in the manifold means into contactwith the shoulder to overlie the smaller bore; and said preventing meanscomprising a distortion of the central portion thereof to provideimperfect seating against the shoulder.

8. In a board as set forth in claim 6, said disc and spring meanscomprising a thin disc of spring-like sheet material with a spiral slotextending from a location near to but offset from its center outwardlythrough plural convolutions, and the disc being supported in the largerbore portion with its outer periphery against the shoulder, the centralportion of the disc being normally out of contact with the shoulder atthe smaller bore and being displaceable by the vacuum in the manifoldmeans into contact therewith; and said preventing means -comprising adistortion of the central portion of the disc to provide imperfectseating against the shoulder.

9. In a board as set forth in claim 6, said disc and spring meanscomprising a tlat disc sized to slide freely in said larger boreportion, a spiral spring having its center attached to the centralportion of the disc and spiralling through plural convolutions awaytherefrom and terminating in an outer convolution sized to grip the Wallof the larger bore portion and disposed at said shoulder, and the springnormally holding the disc remote from the shoulder but yielding topermit flat nesting of its convolutions between the shoulder and thedisc when the latter is attracted toward the former by the vacuummanifold means, said preventing means comprising the nested convolutionsof the spring leaving a leakage space therebetween.

10. In a board as set forth in claim 9, the spiral spring being woundsuch that the space between its convolutions when nested increases fromminimum spacing near the outer convolutions to maximum spacing near theinner convolutions.

11. A vacuum board for holding flexible sheets in a plane, comprising:

(a) a panel member having plural suction holes therethrough, eachincluding a bore extending from the front face of said membertherethrough to the rear and having a shoulder therein at a locationwhere the bore changes from a larger front bore portion to a smallerbore portion extending through the rear of the panel member;

(b) vacuum manifold means on the rear of the panel and communicatingWith said bores;

(c) vacuum-operated valve means in each suction hole and comprising discand spring means contained within a larger portion of the bore, the discmeans having a central portion sized to cover the end of the smallerbore at the -shoulder and having the central portion distorted toprevent perfect seating thereagainst, and

7 the spring means yieldably urging the central portion of the disemeans away from the shoulder and from the smaller bore portion; and

(d) means for `covering the fronts of each of the bores comprisingwashers pressed into the bores flush with the front of the panel memberand having openings of cross-sectional area at least equalling theassociated v'smaller bore portions.

12. In a board as set forth in claim 11, said panel member having anenlarge-ment at the front of each larger bore portion, `said disc andspring means comprising a thin flat dise of spring-like sheet materialwith a spiral slot extending from a location near to but offset from itscenter through plural convolutions to a point near the periphery of thedisc, and the disc being supported at its periphery in said enlargementparallel to and spaced from the shoulder, and the central portion of thedisc vbeing displaceable by the vacuum in the manifold means intocontact With the shoulder to overlie the smaller bore; and said washerbeing pressed into said enlargement against the periphery of the disc.

References Cited by the Examiner UNITED STATES PATENTS CLAUDE A. LE ROY,Primary Examiner.

J. F. FOSS, Assistant Examiner.

1. A VACUUM BOARD FOR HOLDING FLEXIBLE SHEETS IN A PLANE, COMPRISING:(A) A PANEL MEMBER HAVING PLURAL SUCTION HOLES THERETHROUGH, EACHINCLUDING A BORE EXTENDING FROM THE FRONT FACE OF SAID MEMBERTHERETHROUGH TO THE REAR AND HAVING A SHOULDER THEREIN AT A LOCATIONWHERE THE BORE CHANGES FROM A LARGER FRONT BORE PORTION TO A SMALLERBORE PORTION EXTENDING THROUGH THE REAR OF THE PANEL MEMBER; (B) VACUUMMANIFOLD MEANS ON THE REAR OF THE PANEL AND COMMUNICATING WITH SAIDBORES; (C) DISC AND SPIRAL SPRING MEANS IN SAID LARGER BORE PORTION, THEDISC MEANS FITTING SNUGLY THEREWITHIN AND HAVING A CENTRAL AREA LOCATEDOPPOSITE SAID SMALLER BORE PORTION AND URGED AWAY THEREFROM BY SAIDSPRING MEANS, AND SAID DISC AND SPRING MEANS BEING MOVABLE